1. Field of the Invention
The present invention relates generally to flexible containers. Particularly, the present invention relates to fitments for sealed, flexible containers. More particularly, the present invention relates to a sealing method for a fitment to a single or multi-layered flexible container intended for long term oxygen stability.
2. Description of the Prior Art
Pouch-type flexible containers have been used for sterile packaging of various foodstuffs, liquids and other degradable material. These flexible containers are typically made from webs of flexible film that are folded and sealed together along the unconnected peripheral sides. A few medical solutions have been sterilely packaged in pouch-type flexible containers as well as solutions used to insure proper performance of various chemical analyzers.
For example, to insure proper performance of Blood Gas Analyzers, control material is typically run several times per day. This material consists of solutions that have been tonometered to specific values of dissolved oxygen and carbon dioxide concentrations along with specific pH values and electrolyte and metabolic concentrations. For external control samples, the current state of the art is to store the control material in glass ampules. In order to run these controls the operator must break the ampules and manually introduce the samples into the analyzer, typically at predetermined time intervals, three levels of control per shift, three times per day. This approach is time consuming and requires user intervention.
A recent trend in the industry is to automate this process by storing the control material on board the analyzer and automatically running the required controls at preset time intervals. This greatly reduces the amount of time required by the operator. One approach for storing the control material on board the analyzer is to package it in flexible containers such as pouches and docking these pouches to the analyzer. A disadvantage with this approach is that, typically, the pouch material is not as good of a barrier to gas transport as are the glass ampules used for external controls. Examples of various concerns with use of a flexible container are an increase in oxygen of the control material due to oxygen diffusion through the flexible container material, a reduction in oxygen concentration due to a chemical reaction between the control fluid and the flexible container material, etc.
The majority of flexible films used for flexible containers are monolayer PVC films. Recently, a few multiple-layer, extrusion or adhesive laminated films have been developed. These multiple-layer films typically have an inner, solution contacting film layer and an outer barrier layer that can be made of aluminum foil or some other barrier material. The inner, solution contacting layer must be substantially inert to the solution while the outer barrier layer must be durable and also compatible with other materials that may contact or be attached to the outside surface. The flexible container or pouch is formed from flat, film material by heat sealing the edges together and thereby melting the inner plastic layer. These pouches typically require a fitment for accessing the contents of the pouch. For use in blood gas and chemistry analyzers, the pouches require a fitment that docks the pouch to the analyzer and makes the fluid connection. Currently, the fitment is placed at the periphery of the bag between two layers of the bag and the fitment and the inner plastic layer of the flexible container or bag are melted to each other. This requires that the fitment material and the bag material have similar melting points. This limitation requires that the fitment is typically made of a low melting point plastic, such as polyethylene. A primary disadvantage of the fitment material is that the fitment material typically has a higher oxygen permeability than the film material. In other words, the fitment is a “hole” in the sealed bag. The permeability characteristic of the fitment material is much poorer than the similar characteristic for the laminated film used to make the flexible container. Thus, the fitment is often the weakest part of the barrier characteristics of the flexible container. Another disadvantage is that the heat sealing process tends to damage the barrier layer, which can lead to inconsistent performance.
U.S. Pat. No. 5,514,123 (1996, Adolf et al.) discloses a sterile formed, filled and sealed flexible solution container and a sterile administration port assembly which is attached without interrupting the complete sealing of the hermetically sealed fluid container and which allows for the sterile packaging, storage and delivery of a sterile medical solution without heat degradation or oxygen permeation. Particularly, the flexible container is thermally fused to the saddle flange of the administration port assembly.
U.S. Pat. No. 6,142,341 (2000, Uematsu) discloses a spout assembly comprising a spout and a cap. The spout has a cylindrical outer tube to be placed outside a package and a base to be bonded to the inner surface of the package. The cap is separably connected to an extremity of the cylindrical outer tube coaxially with the cylindrical outer tube in a position in which the cap is pushed into the cylindrical outer tube.
U.S. Pat. No. 6,378,731 (2002, Klabes) discloses a pouring spout for a bag, which comprises a spout, which is inserted into a bag opening. The spout is detachably held in the bag opening by a clamping means, such that it is sealed opposite the bag wall.
A disadvantage of the prior art is that fitment attachment requires heat sealing of the fitment to the flexible film material at the periphery of the container. This limits the available material that can be used for the fitment to a low melting point plastic. These materials have relatively high oxygen permeability properties. Another disadvantage is the damage induced to the barrier layer during the heat sealing process to the fitment. A further disadvantage of a mechanical clamping seal of certain prior art is that the clamping mechanism and spout must be connected to the flexible material along the periphery of the pouch.
Therefore, what is needed is a fitment that is made of a low oxygen permeable material for use with flexible containers. What is further needed is a fitment that reduces the damage to the barrier layer of the flexible container when attached. What is also needed is a fitment and flexible container capable of preserving the contents of the flexible container for a longer period of time.